Effect of microstructure on dielectric and fatigue strengths of BaTiO3

In the present study, bulk barium titanate ceramic specimens with bimodal microstructures are prepared and their dielectric and fatigue strengths under an alternating electric field are investigated. It is found that both the dielectric and fatigue strengths decrease with increasing amount of coarse grains. The scatter of the fatigue strength is characterized with the Weibull statistics. The extent of scatter of the fatigue strength data correlates strongly with the size distribution of the coarse grains. Such correlation is resulted from the presence of intrinsic defects within the microstructure. Direct microstructure evidences are provided.